Continuous renal replacement therapy

After its introduction, continuous renal replacement therapy (CRRT) has found widespread acceptance amongst physicians taking care of critically ill patients. Various modalities (haemofiltration, haemodialysis, haemodiafiltration) are used. As for all types of renal replacement therapy, a good functioning vascular access is an absolute requirement. Whether CRRT is to be preferred over intermittent haemodialysis remains a matter of debate, but haemodynamic instability and risk of cerebral oedema are generally considered indications for CRRT. Whereas under-dosing should certainly be avoided, increasing the dose over an actually delivered effluent flow of 20–25 mL/kg/hour does not appear to improve outcome.One of the major drawbacks of CRRT is the requirement for continuous anticoagulation. Citrate anticoagulation is gaining popularity and represents a valuable alternative, especially in patients with bleeding risk. Other potential complications of CRRT include thermal, nutrient, and drug losses, and acid–base and electrolyte disturbances.